Permanent dam and weir



Jul 24,-1928.. 1,678,515

S. HCiYER PERMANENT DAM AND WEIR Filed March 10, 1925 of the river.

Patented July 24, 1928. V

UNITED STATES sreunn Horns, or OSLO, uonwnx.

if i 1,678,515

PERMANENT DAM AND WEIR.

Application filed March 10, 1925, Serial No. 14,382, and in Norway March 12, 1924.

In dams of concrete or the like the material of the dam is liable to be deteriorated by water passing in small quantities through the dam, thus easily forming passages for ever larger amounts of water. When a considerable leakage has been formed, this leakage may increase rapidly and damage may arise.

In most cases it is very diflicult to repair leakages ofthis kind, and such repairs necessitate use of very large coiferdams or sheetpiling or otherwise the whole basin mustbe emptied.

The present invention has for its object an improvement in dams and weirs, whereby the risk of total break down is minimized and possibility is obtained of inspecting the dam and repairing the same if need arises, without resorting tothe steps above mentioned.

Dams and weirs made in accordance with the present invention will for this reason have a considerably longer life than those of the type at present known.

The improvement according to the pres ent invention consists in placing immediately in front of the ordinary dam (working darn) a second or safety dam which is suiliciently strong to take up the water pres sure, if the first mentioned dam or working dam should break or want repair.

This second or safety dam in accordance with the present invention may be made equal or practically equal to the working dam, but this is not absolutely necessary. It may be sufiicient to have the safety dam high enough and strong enough to function at low water levels, these periods being then utilized for inspecting and repairing the working dam.

As the narrow space between the two dams will normally always be filled with water to approximately the same level as the level of the water in front of the dam,

the safety dam will therefore not under ordinary circumstances be exposed to water pressure and will in consequence of this not be'subject to'deterioration. This is also the case at the points where the safety dam engages the rock at the sides or at the bottom The safety dam is only exposed to pressure wear and destruction during the periods when the working dam is 7 under repair.

ordinarily has a life of 50 years, the working dam obviously may be rebuilt or sufiiciently overhauled after the lapse of 50 years, letting the safety dam function under the periods of rebuilding or overhauling the ordinary working dam, without necessitating interruption of the power station or without the use of a 'cofferdam or sheet pilings.

If the re-building or the overhauling of the working dam takes one year, the safety dam should be able to stand 50 overhauling or re-building periods, i. e. 2,500 years, but the main advantage of the present arrangement is, however, considered to be that the leakages and weak points may be repaired soon as they are observed, whereby the life of the Working dam is exceedingly increased.

In case the working dam should break, the Water between the two dams will run away, and the safety dam will automatically enter into function.

It may be considered as apractical impossibility that both dams should break at the same time.

The present construction is considered as an important improvement in connection with arch dams, serving to dam the whole yalley or gorge by means of an arched wall 1n one span.

Dams of this kind rightly have been considered risky propositions, but by using the present invention, large dams of this kind may be utilized without running any risk at all, and in many cases the construction will nevertheless be cheaper, more durable and easier to keep up than the correspond ing dam of the gravitation type.

However, the most important application of the invention lies in its use with buttress dams or weirs, having inclined arches or flat slab sections mounted on the buttresses.

The two dam walls, i. e. the two sets of arched or flat sections forming the working and the safety dam, have common buttresses to carry both dam walls, even in case the working and safety dam wall may he made substantially equal, or the safety dam wall may be made lower and in consequence also lighter than the working dam wall, so as to take over the function of the working dam only at lower water levels.

If part of the working dam needs repair, the whole working dam may be put out of commission, and its function is then taken over by the safety dam or one or more sections only of the working dam may be emptied and the corresponding sections of the safety dam brought into use.

The drawing, Figs. 1 and 2, shows a vertical section and a plan of an arch' dam in accordance with the present invention.

Fig. 3 is a vertical section through a buttress dam or weir in accordance with the in v ention, and

' Fig. 4 is a plan of the same.

On Figs. 1 and 2 the working dam is indicated with 1 and the safety dam with 2.

The space between the dams is filled with watersubstantially to the same level as the upstream waterlevel. If the working dam breaks or is to be repaired, the water between the two dams is dissipated, whereupon the hydrostatic balance on the dam 2 is upset, and it immediately acts as an ordinary impounding closure, and successfully takes over all the pressure formerly resisted by dam 1.

In the form of the invention illustrated on Figs 3 and l the normal working dam is represented by the arched wall sections 1", which are supported in the ordinary manner in an inclined position on buttresses l The buttresses 4 are extended in front of the working dam l, and serve also to support the safety dam, comprising arches 2 The several channel-shapedspaces between arches 1 and 2 and two adjacent buttresses P may be interconnected.

Although it is statedhere thatthe downstream or rear dam is the working dam and the upstream dam the safety dam, the dam construction obviously may also for a shorter or longer period be utilized with the downstream dam as a reserve or an auxiliary,

The first mentioned mode of utilizing the system is, however, preferable.

Claims 1. A substantially permanent dam, comprising in combination, a closure section coextensive with the width of a stream, and having another cooperating closure section upstream therefrom at a distance not greater than the height of said first closure section, said closure section having a height not less than the height of said second closure sec tion, the space thereby formed between said closure sections being connected to the stream upstream of the dam, whereby said space is normally filled with a body of water exerting a back pressure on said second closure section sufficient to relieve said section of all unbalanced water pressures,

said water space being emptiable by the.

set forth in claim 1, the combination with a plurality of buttresses of at least two sets of parallel dam wall sections located one in front of the other between adjacent buttresses and supported thereby.

In testimony that I claim the foregoing as my invention, I have signed my name.

SIGURD HOYER. 

